Take care of Shelly/Twisted Shelly/Both game. At first, you have Shelly that you can adopt, ofc. However, you have a secret option that is ichor. You smother her in the ichor and she becomes Twisted Shelly. When she transforms, she's really angry at you, for example, she tries to bite you when you pick her up and has an aggravated face, growling at you. But at the very least, you can just make a Take Care of Shelly game